Finding the Fourth Proportional to 1,111.78, 1,534.74 and 663.80

Step by Step Solution

1. Step 1: Write the proportion equation
   1,111.78 : 1,534.74 = 663.80 : x
2. Step 2: Convert to fraction form
   1,111.78/1,534.74 = 663.80/x
3. Step 3: Cross multiply
   1,111.78x = 1,534.74 × 663.80
4. Step 4: Simplify right side
   1,111.78x = 1,018,760.41
5. Step 5: Solve for x
   x = 1,018,760.41/1,111.78
6. Step 6: Final answer
   x = 916.34